Here is the thing: it's super easy to lose money, at least on paper, as a real estate professional. This is because the cost of the building you buy is evenly divided up over a number of years and that pro-rated cost is subtracted from your income along with your other expenses (taxes, repairs, etc).
It is so easy, in fact, that partnerships that owned real estate were very popular back in the ‘80s. High earners would buy a partnership interest containing some real estate, and those paper losses offset some of their real income. It was such a common and such an abusive tax dodge that an entirely new class of income was created...its “passive income” from rental real estate activities and now very few people can use these fake losses to offset their real income.
There are still a few people who can, though...a very small group of people designated as “real estate professionals” by the IRS. The rules are very strict about what you have to do to be a real estate professional.
The one that is going to be problematic for Trump is the requirement that you spend more than half your working time engaged in real-estate-related activities. Really. And the IRS is very insistent about documentation of this.
So, what's it going to say under “occupation” on Donald Trump’s tax return in 2017? Is it going to say “Real Estate Professional”? Or is it going to say “President of the US”? Because if it's the former, Donald Trump is going to have to sign his tax return, under penalty of perjury, saying that presidenting is a part-time side endeavour, not his real job. And if it's the latter, he's going to be paying Federal taxes — substantial ones, in the tens of millions of dollars — for the first time in a very long time.